USA Standard NP246 Transfer Case Bearing Kit ZTBK351

This is the bearing, gasket and seal package for rebuilding a New Process 246 transfer case, the electronic push-button AutoTrac unit GM ran behind the 4L60E and 4L80E in 1998-2005 Silverado, Sierra, Tahoe, Yukon, Suburban, Escalade and Avalanche. USA Standard part number ZTBK351. It covers the bearings and the full gasket and seal set, so the case goes back together sealed instead of weeping at the halves.

The NP246 fails in a predictable pattern. The pump rubs a hole through the rear case half, fluid level drops, and the bearings and clutch pack cook. By the time you have it on the bench with the halves split, the input and mainshaft bearings are usually rough and the seals are hard. Replacing them piecemeal never works out cheaper than doing the whole set at once while the case is apart.

Bench notes: the input bearing in this kit is the 16 mm (0.63 in) width version used on 1998-2005 cases, so measure the old bearing before you order if your case is a later unit or a Dodge application. Drain and split the case, pull the chain and mainshaft, press the old bearings out with a driver set, then clean both halves and check the rear half for pump rub before you install anything new. A grooved or thin rear half needs to be replaced or a pump saver plate fitted, otherwise the new bearings will be back in the same condition.

Kit weight is about 5 lb. This is the bearing and seal set only. Clutch plates, the chain, and the pump are ordered separately if the teardown shows they are worn.